Hindustani classical music tradition is based on some important princi

ples.
It’s very important for learners to go through these principles thoroughly. Pandit V.N. Bhatkhande
has described about these principles on his book "Kramik Pustak Malika
- Part V". Having that as base, the forty principles of Hindustani classical music are given below:

1. Base of Hindustani classical music i.e. "Bilawal Thaat" is to be considered as shudh (pure) Thaat. Because Bilawal Thaat is the only Thaat that has all 7 shudh (pure) swaras.

14. Sa, Ma and Pa these three swaras usually have their importance in the raagas which are sung or played in the third half of the day and night.

15. Swar "Tivra Ma" is mostly found in night raagas. In day raagas usage of this swar is very little.

16. "Sa – Ma – Pa" swaras from this combination can be seen in uttrang and purvang part of saptak. The raagas which can be sung or played at any time, those raaga’s vadi swar is one of these swaras.

17. In any raag swar Ma and Pa both cannot be excluded. If swar Ma is excluded in a raag then swar Pa will be included and vice-versa.

18. In any raag swar Sa is not excluded.

19. In raagas usually a swar with two forms (Komal - Tivra) should not be included together but some raagas like raag Lalit are exception to this principal.

20. Raagas sound beautiful if they are sung on their specified time, but while performing on the stage this rule could be broken.

21. Swar Tivra Ma and Komal Ga in one raag are found less.

22. Raagas with both Ma (Shudha and Tivra) are usually somewhat similar to each other. Difference in these raagas is usually found in aaroh.

23. Raagas which are sung and played in the first half of the night and have both madhayam (Ma) have the simple rule that shudha Ma is used in aaroh and avroh as well, but Tivra Ma can be seen only in aaroh.

24. Raagas which are specified to be sung and played in the first half of the night,have swar Ni as Vakarswar in Aaroh and swar Ga (Vakar) in Aavroh. Usually in aaroh of these raagas swar Ni is rarely seen.

25. In Hindustani classical music tradition raagas are given more importance as compared to taals. It is the other way round in the carnatic classical music tradition, Taals are given more importance compared to raagas. there.

26. The importance of the pooravang Raagas is seen in Aaroh and the magic of the utterang Raagas is seen in their Aavroh.

27.Poorvang-raag and uttarang-raag can be born from every Thaat usually..

28. In serious kind of raagas swar Sa Ma and Pa are very important and more importance of these swaras lies in mandra saptak, but this is not seen in shudra raagas.

29. In sandhi prakash raagas there is an essence of peace. Raagas with shudha "Re Gha Dha" represent beauty and laughter and raagas which have komal "Ga-Ni" represent braveness and danger.

30. While entering from one Thaat’s raagas into another Thaat’s raagas "Permal Praveshak" raagas are sung and played.

31. Sandhiprakash raagas are sung during sunrise and sunset and after that, raagas with shudha "Re-Dha" are sung or raagas with Komal "Ga-Ni" are sung.

32. Raagas which have komal Ni. e.g. Raagas from thaat, Kafi and Khamaj, have sometimes shudha Ni used ,in them.

33. In any raag when swaras are sung or played then it becomes less, more or equal to become week, strong or equal.

34. Combination of two, three or four swaras is known as taan and not as a raag.

35. Raagas which are sung after 12 pm and after 12 am, have"Sa Ma Pa" consistently stronger in them.

36. Raagas which are specified to be sung in the noon in their aaroh swar "Re-Dha" are week or excluded and in these raagas swar Re and Ni are used more.

37. In raagas which include vadi swar from "Sa Ma Pa" are usually serious in nature.